<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        [v-model]{
            width: 500px;;
        }
    </style>
</head>

<body>
    <div id="app">
        <input type="text" v-model="msg">
        <span>{{msg}}</span>
    </div>
    <script>
        let data={};

        Object.defineProperty(data,'msg',{
            set:function(){
                console.log('有人设置了')
            },
            get:function(){
                console.log('有人调用了')
                return 123
            }
        })
        //data.msg='aaa'
        data.aaa=123;
        //console.log(data.msg);
    </script>
</body>

</html>